Access To Variables In Post Controllers

Is there any nice way to access variables defined in controller.php (core file) from within controller.post.php in addon without modifying the cores??

Sure:

$data = Registry::get('view')->getTemplatelVars('variable name');
// modify $data
Registry::get('view')->assign('variable name', $data);

There is a typo in the code. It should be

$data = Registry::get('view')->getTemplateVars('variable name');
// modify $data
Registry::get('view')->assign('variable name', $data);

And do not forget to add this line of code to the top of the file

use Tygh\Registry;

thx